Abstract: A combustible mixture is compressed in the crankcase of a four-stroke cycle engine and forced into a boost plenum which houses the camshaft. The compressed mixture is metered by a throttle to intake valves of the engine. The engine is constructed from identical engine block elements rotated and joined to enclose the centrally disposed crankcase and common boost plenum with the cylinders horizontally opposed.

Abstract: A four-stroke internal combustion engine is supercharged by admitting fuel-air mixture into the engine crankcase and compressing the mixture on the down stroke of the piston. The engine cylinder, and the piston disposed therewithin, are of stepped configuration defining a combustion chamber above a smaller, top piston portion, and an annular chamber above a larger, lower piston portion. Compressed mixture from the crankcase is admitted to a pressure reservoir for supply to the combustion chamber via an intake valve and a throttle valve. The crankcase is either supplied with fuel-air mixture from the annular chamber, or supplies fuel-air mixture to the reservoir via the annular chamber, so as to provide two stages of compression.

Abstract: An internal combustion engine comprises a plurality of cylinders disposed in circular array, each having a piston slidably received therewithin to define a combustion chamber. Connecting rods affixed to the pistons are provided with cam follower means for engaging a cam surface on a drum disposed coaxially with the aforementioned array, the cam follower means engaging different portions of the cam surface for causing the drum to rotate as the pistons fire. The drum is axially movable with respect to the array of pistons whereby the compression ratio of the engine is readily changed. Supercharging chambers are defined on opposite sides of said pistons from the combustion chambers for compressing a fuel-air mixture which may then be received into pressure tanks associated with the respective cylinders for delivery to the combustion chambers. The piston ends have helical surfaces for producing a swirling of gases within the combustion chambers.